Characterization of the CVD Graphene Monolayer as an Active Element of a One-Port Microwave Device

Modeling and Analysis of Sub-Millimeter-Wave Graphene Switches for On-Wafer Coplanar Transmission Lines

“…external field biasing or heating). Such materials include ferrite [31], liquid crystals [32], molybdenum disulfide (MoS2) [33], black phosphorus (BlPh) [34], vanadium dioxide (VO2) [35]- [37], and graphene (GR) [38]- [49]. In the literature, MoS2 and BlPh switches are currently limited to lower frequencies (<100 GHz) due to their high intrinsic impedances that demand for thin and long active device shapes to avoid excess losses; however, these configurations are highly affected by parasitics that become pronounced in high frequencies [33] [34].…”

“…1. Graphene is a 2D material that exhibits sheet resistance tunability over a great bandwidth (DC-1.5 THz) with the use of external biasing similarly to field-effect-transistors [38]- [49]. Additionally, the implementation of large-scale graphene reconfigurable apertures has been recently enabled with the development of a high-yield nanofabrication process that offers more than 92% yield over a large area [39] [40].…”

“…Even though graphene has a relatively low switching ratio Rbiased=300 Ω/□ and Runbiased=1,500 Ω/□ [41]- [44], these sheet resistances are considerably lower than MoS2 and BlPh, leading to designs with fewer constraints regarding the channel/active device size, therefore fewer parasitic effects at mmWave/THz bands. Several studies that propose graphene-loaded topologies include attenuators, switches, and reconfigurable power dividers [45]- [49]. These works include both experimental designs and/or theoretical studies for series or shunt configurations; however, an insight on the expected performance based on the configuration (series versus shunt topology) and the design parameters (e.g.…”

“…A partial study with respect to the aforementioned parameters is carried out in [46], where the performance of a series graphene switch is studied only for variable graphene patch widths. On the other hand, existing studies use equivalent models for graphene devices [47]- [49]. Namely, in [47] an equivalent model is used to extract the graphene sheet impedance values from the measured Sparameters of a microstrip attenuator.…”

“…Moreover, in [48], an equivalent model approach is exploited to identify the losses in GL TLs, by carrying out full-wave simulations and then using the ABCD parameters to extract the complex TL characteristics (complex-propagation constant and -characteristic impedance) for different frequencies. Finally, in [49] a one-port GL device is proposed and an equivalent model is used to extract the graphene sheet impedance values without investigating the effects of patch geometry on device performance. Nevertheless, no study examines in depth the switching performance with respect to the affecting parameters, especially for the various coplanar transmission line topologies presented in this work.…”