Transport Conductivity of Graphene at RF and Microwave Frequencies

TL;DR

This study measures graphene's RF and microwave conductivity, revealing that its intrinsic conductivity remains constant across frequencies up to 13.5 GHz, which is crucial for high-speed electronic device design.

Contribution

The paper demonstrates that graphene's intrinsic conductivity is frequency-independent up to 13.5 GHz, providing insights into its AC transport properties and modeling as a resistive-capacitive network.

Findings

Intrinsic conductivity is frequency-independent up to 13.5 GHz.

Apparent resistance shows quadratic frequency dependence due to parasitic impedances.

Graphene's AC conductivity aligns with Drude model predictions.

Abstract

We measure graphene coplanar waveguides from direct current (DC) to 13.5GHz and show that the apparent resistance (in the presence of parasitic impedances) has an quadratic frequency dependence, but the intrinsic conductivity (without the influence of parasitic impedances) is frequency-independent. Consequently, in our devices the real part of the complex alternating current conductivity is the same as the DC value and the imaginary part~0. The graphene channel is modelled as a parallel resistive-capacitive network with a frequency dependence identical to that of the Drude conductivity with momentum relaxation time~2.1ps, highlighting the influence of alternating current (AC) electron transport on the electromagnetic properties of graphene. This can lead to optimized design of high-speed analogue field-effect transistors, mixers, frequency doublers, low-noise amplifiers and radiation detectors.