Conductivity extraction of thin Ti3C2T<i>x</i> MXene films over 1–10 GHz using capacitively coupled test-fixture

Thin films of two-dimensional MXene (Ti3C2Tx) are evaluated in terms of their conductivity over the radio frequency (RF) range of 1–10 GHz using a custom designed test fixture. A contactless method is developed for extracting the conductivity of MXene films of various thickness (1.0–4.3 μm) at RF frequencies. Open ended MXene transmission lines with various thicknesses are spray-coated on polyethylene terephthalate substrates capacitively coupled to a copper transmission line test fixture realized on a RT/duroid (filled polytetrafluoroethylene composite laminate) substrate to provide solderless repeatable RF connection. The extraction process is based on the least squares error method of curve fitting to minimize the difference between the full wave numerically simulated scattering parameters and the measured values of the test circuit for various samples. RF characterization was performed for three MXene samples, with thicknesses of about 1.0, 1.5, and 4.3 μm to extract the corresponding conductivity. Moreover, MXene performance was compared against copper and graphite films. The highest conductivity of 1.2 × 106 S/m was extracted for the 4.3 μm thick Ti3C2Tx film. The extracted MXene conductivity is used to predict the quality factor and efficiency of antennas. This study suggests that MXene films are attractive for RF applications and can be used as conductive layers on 3D-printed RF circuits.