Mapping the conductivity of graphene with Electrical Resistance Tomography

Abstract

Electronic applications of large-area graphene films require rapid and accurate methods to map their electrical properties. Here we present the first electrical resistance tomography (ERT) measurements on large-area graphene samples, obtained with a dedicated measurement setup and reconstruction software. The outcome of an ERT measurement is a map of the graphene electrical conductivity. The same setup allows to perform van der Pauw (vdP) measurements of the average conductivity. We characterised the electrical conductivity of chemical-vapour deposited graphene samples by performing ERT, vdP and scanning terahertz time-domain spectroscopy (TDS), the last one by means of a commercial instrument. The measurement results are compared and discussed, showing the potential of ERT as an accurate and reliable technique for the electrical characterization of graphene samples.

Case studies of electrical characterisation of graphene by terahertz time-domain spectroscopy

“…Values of σ DC extracted from THz-TDS conductivity spectra following the Drude model have been validated several times against Hall and M4PP measurements [6,8,11,33,47]. There is however comparatively limited data available [62,71] for measurements of graphene whenσ s (ω) does not appear to follow the Drude model and in particular for measurements at 4 inch wafer-scale.…”

Recommended implementation of electrical resistance tomography for conductivity mapping of metallic nanowire networks using voltage excitation

“…Electrical Resistance Tomography (ERT, and its counterpart in the ac regime, Electrical Impedance Tomography, EIT 1 – 3 ) is a technique that determines a spatial map of the conductivity of an object by performing electrical resistance measurements between electrodes on its boundary. ERT was originally developed as a tool for physiology monitoring 4 and earth science 5 , but later it has been successfully applied to the electrical characterisation of silicon wafer for electronics 6 , composite materials 7 , thin films 8 and graphene 9 . ERT can provide accurate quantitative results in simple implementations with commercial instrumentation 8 , 9 ; with dedicated hardware, it can reach a refresh speed in the ms range 10 .…”

“…ERT was originally developed as a tool for physiology monitoring 4 and earth science 5 , but later it has been successfully applied to the electrical characterisation of silicon wafer for electronics 6 , composite materials 7 , thin films 8 and graphene 9 . ERT can provide accurate quantitative results in simple implementations with commercial instrumentation 8 , 9 ; with dedicated hardware, it can reach a refresh speed in the ms range 10 . At the best of our knowledge, to date little evidence of electrical mapping of metallic nanowire networks (NWN) is available in literature 11 .…”

Shape Reconstruction Using Boolean Operations in Electrical Impedance Tomography

“…The first practical realization of a medical EIT system was detailed in the 1980s by Barber and Brown [2] at the Department of Medical Physics and Clinical Engineering, Royal Hallamshire Hospital in Sheffield (UK). Nowadays, EIT has attracted considerable research interest, and is broadly applicable in the field of medical imaging [3]- [6] and other disciplines such as process tomography [7] and non-destructive testing [8], [9]. For state-of-the-art reviews of EIT, see e.g.…”