Contact-free sheet resistance determination of large area graphene layers by an open dielectric loaded microwave cavity

Shaforost, Olena; Wang, K; Goniszewski, Stefan; Adabi, Mohammad; Guo, Z. H.; Hanham, Stephen M.; Gallop, John; Líu, Hao; Klein, N.

doi:10.1063/1.4903820

Cited by 32 publications

(24 citation statements)

References 30 publications

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“…The σ G of SiC/G is almost an order of magnitude smaller than σ G of SL-CVD/G, and about 28 times smaller than σ G of ML-CVD/G. Moreover, the presented surface conductance results only qualitatively agree with the previously published data for similar graphene materials [7–9]. …”

Section: Resultssupporting

confidence: 44%

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Surface conductance of graphene from non-contact resonant cavity

et al. 2016

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A method is established to reliably determine surface conductance of single-layer or multi-layer atomically thin nano-carbon graphene structures. The measurements are made in an air filled standard R100 rectangular waveguide configuration at one of the resonant frequency modes, typically at TE103 mode of 7.4543 GHz. Surface conductance measurement involves monitoring a change in the quality factor of the cavity as the specimen is progressively inserted into the cavity in quantitative correlation with the specimen surface area. The specimen consists of a nano-carbon-layer supported on a low loss dielectric substrate. The thickness of the conducting nano-carbon layer does not need to be explicitly known, but it is assumed that the lateral dimension is uniform over the specimen area. The non-contact surface conductance measurements are illustrated for a typical graphene grown by chemical vapor deposition process, and for a high quality monolayer epitaxial graphene grown on silicon carbide wafers for which we performed non-gated quantum Hall resistance measurements. The sequence of quantized transverse Hall resistance at the Landau filling factors ν = ±6 and ±2, and the absence of the Hall plateau at ν = 4 indicate that the epitaxially grown graphene is a high quality mono-layer. The resonant microwave cavity measurement is sensitive to the surface and bulk conductivity, and since no additional processing is required, it preserves the integrity of the conductive graphene layer. It allows characterization with high speed, precision and efficiency, compared to transport measurements where sample contacts must be defined and applied in multiple processing steps.

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Section: Resultssupporting

confidence: 44%

“…A similar technique operating at 10.5 GHz has been presented in Refs. [8] and [9]. The method measures the frequency shift and the quality factor of a dielectric post resonator, referencing the specimen surface resistance to the electrical characteristics of the substrate.…”

Section: Introductionmentioning

confidence: 99%

Surface conductance of graphene from non-contact resonant cavity

et al. 2016

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“…In several previous studies, complex permittivity measurements with microwaves were performed to derive the conductivity of graphene, but the charge transport characteristics were not discussed . Herein, we apply the FI‐TRMC technique with ≈9‐GHz microwave probes to assess the local kinetic motion of charge carriers on graphene with controlled domain sizes of 6–30 µm; these are competitive to the mean free path of electrons that range from several micrometers derived from the turn‐over time in the GHz regime as ≈100 ps.…”

Section: Introductionmentioning

confidence: 99%

Relaxation of Plasma Carriers in Graphene: An Approach by Frequency‐Dependent Optical Conductivity Measurement

Choi

Nishiyama

Ogawa

et al. 2018

Advanced Optical Materials

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resulting in ultrahigh carrier mobilities, long mean free paths, and anomalous quantum Hall effects. [3][4][5][6][7] The most important advantage of graphene is the tunability of the carrier densities, which can be easily controlled by a gate bias or doping. [8][9][10][11][12] Consequently, graphene has been applied as convenient tunable terahertz (THz) metamaterials. [9,10,13,14] In photonics, the optical properties of graphene have been discussed with the surface plasmon model, corresponding to the Drude model with the free carrier concept. In general, in the plasmon model, the restoring force by the displacement from equilibrium is neglected to simplify the solution of the Maxwell equation. It has successfully been applied to the analysis of optical conductivity in metals including graphene over the THz regime [15][16][17][18] as the frequency of electromagnetic waves is significantly higher, compared to the plasma frequency. Recently, the applications of graphene have been extended to microwave absorption in the gigahertz (GHz) regime. [19,20] However, in most of these studies, the optical conductivity of graphene, related to the optical absorption, is discussed with the Debye model [21] or free carrier model. [22] The effective mass of electrons in graphene is extremely small, resulting in a high plasma frequency, comparable to the GHz regime. Hence, the analysis of the optical conductivity of graphene in the GHz regime should be modified from the free carrier model to the plasma carrier model considering the restoring force.In contrast, the field-induced time-resolved microwave conductivity (FI-TRMC) technique has recently been applied to complex permittivity analysis for organic semiconductors, leading to the assessment of the trap depth for charge carriers. [23] FI-TRMC is a microwave-based alternating current technique to evaluate the dielectric loss of materials with a resonant cavity. [23][24][25][26][27] In contrast to direct current (DC) methods represented by field-effect transistor (FET) and Hall effect measurements, FI-TRMC is advantageous in that it avoids the effect of extrinsic factors because of the small displacement distance of charge carriers. [28] For complex permittivity analysis with FI-TRMC, the real change in permittivity is estimated simultaneously with the dielectric loss, providing a detailed range of charge transport characteristics in the materials. FI-TRMC is suitable for investigation of the electronic properties The relaxation time and mobility of electrons on graphene are deduced quantitatively by complex permittivity analysis with microwave dielectric loss spectroscopy. Hexagonal graphene sheets with uniform domain sizes from 6 to 30 µm, which target the mean free path of electrons on graphene based on the significantly longer turnover time of microwave probing at gigahertz (GHz) frequencies as compared to the relaxation time of electrons, are employed to determine the factors for carrier relaxation at the intradomain and grain boundaries. The changes in the complex permittiv...

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“…An alternative method for mapping the sheet resistance of graphene films is using micro four-point probes (M4PP) 15,16 . Recently the use of microwave cavities [16][17][18] and Terahertz time-domain…”

mentioning

confidence: 99%

Towards standardisation of contact and contactless electrical measurements of CVD graphene at the macro-, micro- and nano-scale

Melios

Huáng

Callegaro

et al. 2020

Sci Rep

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Graphene has become the focus of extensive research efforts and it can now be produced in waferscale. for the development of next generation graphene-based electronic components, electrical characterization of graphene is imperative and requires the measurement of work function, sheet resistance, carrier concentration and mobility in both macro-, micro-and nano-scale. Moreover, commercial applications of graphene require fast and large-area mapping of electrical properties, rather than obtaining a single point value, which should be ideally achieved by a contactless measurement technique. We demonstrate a comprehensive methodology for measurements of the electrical properties of graphene that ranges from nano-to macro-scales, while balancing the acquisition time and maintaining the robust quality control and reproducibility between contact and contactless methods. the electrical characterisation is achieved by using a combination of techniques, including magneto-transport in the van der pauw geometry, tHz time-domain spectroscopy mapping and calibrated Kelvin probe force microscopy. The results exhibit excellent agreement between the different techniques. Moreover, we highlight the need for standardized electrical measurements in highly controlled environmental conditions and the application of appropriate weighting functions.The unique properties of graphene 1 and the increasing demand for large-scale production were the reason for the development of various industrial methods to grow this material. One of the most promising methods is the use of CVD to grow graphene onto various metallic substrates. In CVD growth, graphene is grown on the surface of the metal after hydrocarbons decompose 2 . The most promising metal substrate used until now is Cu 3 , however graphene is currently grown also on Ni(111) 4-6 , Ru(0001) 7 , Pt(111) 8,9 , and Ir(111) 9-11 . Subsequently to the growth process, for graphene to be use in electronic applications, it needs to be transferred on an insulating substrate (i.e. Si/SiO 2 , quartz or polyethylene terephthalate (PET), which is a transparent and flexible substrate). The already happening now use of graphene in RF electronics 12 , integrated circuits 13 and optoelectronics 14 has triggered impressive progress in large-scale production, however the community still lacks standardised electrical measurements to extract useful parameters such as carrier concentration, mobility and sheet resistance, all of those are often presented as figures-of-merit of the graphene quality. Currently, the most widely used method for electrical characterisation involves magneto-transport measurements in lithographically patterned Hall bars to extract carrier concentration, mobility and resistance. However, this method is not suitable for high throughput characterisation and often the measured graphene is significantly altered due to the microfabrication processes, in which case the electrical properties of the pristine transferred graphene are different from the ones measured. An alternative method fo...

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Contact-free sheet resistance determination of large area graphene layers by an open dielectric loaded microwave cavity

Cited by 32 publications

References 30 publications

Surface conductance of graphene from non-contact resonant cavity

Surface conductance of graphene from non-contact resonant cavity

Relaxation of Plasma Carriers in Graphene: An Approach by Frequency‐Dependent Optical Conductivity Measurement

Towards standardisation of contact and contactless electrical measurements of CVD graphene at the macro-, micro- and nano-scale

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