Fabrication and characterization of GNR transmisson lines for MMIC applications

In this paper graphene nanoribbons (GNRs) are proposed as a new conductive material for monolithic microwave integrated circuit (MMIC) transmission lines to replace existing materials, because they have the potential to offer better performance. Multi-layered graphene films were grown on SiO₂/Si wafers coated with Ni using chemical vapour deposition. Co-planar GSG electrodes of various widths and lengths were patterned on the graphene film using electron beam lithography (EBL) and wet chemical etching to form the transmission lines compatible with microwave wafer probes used in the measurements. The lines and the underlying SiO₂/Si layers were then modeled as thin film co-planar waveguide (TFCPW) before characterization and their microwave behavior was simulated using CST Microwave Studio electromagnetic simulator. By curve-fitting the experimental results with simulation, graphene parameters were subsequently extracted. From I-V measurements the conductivity was found to be 2.89 × 10⁷ S/m and scattering parameter measurements of the samples obtained at frequencies up to 20 GHz show that GNR has high potential for transmitting signals at GHz frequencies.