Contactless Electrical Resistance of 2D Materials Using a Rutile Resonator

Abstract

Measuring the electrical surface resistance of 2D materials without contact can provide a method for obtaining their intrinsic characterization. Herein, the aim is to show that a rutile dielectric resonator (RDR) can be used to measure the electrical surface resistance of conducting coatings deposited on substrates, at the resonance frequency. Moreover, it is known that the substrate exerts a strong influence capable of intrinsically modify the properties of 2D materials, as found in graphene. The RDR method is used for different samples of metals (Cu, Mo, Ti, and brass), carbon nanotubes (bucky paper), a film of compacted graphene flakes, a film of compacted graphene oxide flakes, and graphene obtained by chemical vapor deposition (CVD) on different substrates (SiO2/Si, quartz, and polyethylene terephthalate [PET]). The results show that reasonable values can be obtained for thin conducting materials with a thickness of not less than a few micrometers. In the case of graphene grown on a substrate, the presence of graphene is clearly detected but the resistivity value cannot be extracted.

High‐Frequency Contactless Characterization of 2D Materials. Graphene, WS2

“…Summary of the resonance frequency f 0 , the quality factor Q, the surface resistance R s , and the resistivity ρ obtained for brass, copper, and the graphene-based samples. [14] Sample…”

“…Samples were fixed with a pair of bulk brass blocks and the electromagnetic field was generated by a pair of coaxial cables with coupling loops at the end (see Figure 5 ). [ 7,14 ]…”

“…Samples were fixed with a pair of bulk brass blocks and the electromagnetic field was generated by a pair of coaxial cables with coupling loops at the end (see Figure 5). [7,14] The experimental process consists on measuring the spectrum of the S 21 parameter with a vector network analyzer to obtain the resonance frequency, f 0 , and the quality factor, Q, of the resonator. The resonance mode used was the TE 011 mode and f 0 varies from 8.5 to 9.5 GHz.…”

“…The quality factor of the resonator is a measure of the ratio between the energy stored and the energy dissipated by the resonator and could be obtained from S 21 spectrum by dividing the resonance frequency by the bandwidth at 3 dB. Equation (14) shows the relation between the surface resistance of the surfaces enclosing the cavity (the sample) and the quality factor of the resonator. [7] 1 Q…”

“…Despite the fact that it is possible to measure with a unique sample, as shown in ref. [14], RDR method needs two identical samples to obtain the best results (using only one sample increases the error sources and needs more measurement stages). THz-TDS method requires only one sample of the 2D material, but a bare substrate is also needed, and the minimum number of required measurements is 3, in comparison with RDR method, which just needs a unique measurement in the case of enough thick samples.…”