Extraction of Graphene's RF Impedance through Thru-Reflect-Line Calibration

Graphene has unique properties that can be exploited for radiofrequency applications. Its characterization is key for the development of new graphene devices, circuits, and systems. Due to the two-dimensional nature of graphene, there are challenges in the methodology to extract relevant characteristics that are necessary for device design. In this work, the Thru-Reflect-Line (TRL) calibration was evaluated as a solution to extract graphene's electrical characteristics from 1 GHz to 65 GHz, where the calibration structures' requirements were analyzed. It was demonstrated that thick metallic contacts, a low-loss substrate, and a short and thin contact are necessary to characterize graphene. Furthermore, since graphene's properties are dependent on the polarization voltage applied, a backgate has to be included so that graphene can be characterized for different chemical potentials. Such characterization is mandatory for the design of graphene RF electronics and can be used to extract characteristics such as graphene's resistance, quantum capacitance, and kinetic inductance. Finally, the proposed structure was characterized, and graphene's resistance and quantum capacitance were extracted.

Automated summary

Graphene has unique properties that are ideal for radiofrequency applications, but its characterization presents challenges due to its two-dimensional nature. This study evaluates the Thru-Reflect-Line calibration as a solution for extracting graphene's electrical characteristics, and identifies the necessary requirements for the calibration structures. The inclusion of thick metallic contacts, a low-loss substrate, and a short and thin contact is crucial for accurately characterizing graphene. Additionally, a backgate must be included to account for the dependence of graphene's properties on the applied polarization voltage.