Microwave characterization of graphene nano-ribbon transmission lines using an improved calibration technique

• Published in: IEEE Region 10 Annual International Conference, Proceedings/TENCON
• Main Author: Kara M.H.; Emhemed A.A.; Rahim N.A.A.; Mahmood M.R.; Awang Z.
• Format: Conference paper
• Language: English
• Published: Institute of Electrical and Electronics Engineers Inc. 2015
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84940549429&doi=10.1109%2fTENCON.2014.7022343&partnerID=40&md5=1a40e0029016a234f64e691519051c2f

In this paper we report an investigation on the possibility of using graphene nano-ribbon (GNR) as a conductive material in MMIC applications in the range of 2-20 GHz. GNRs provide an advantage to the applications of MMIC transmission lines, as the line impedance can be controlled by their dimensions. The structural characteristics of graphene films grown on Ni film deposited on Si/SiO2 wafers after nickel removal were analyzed by optical, FSEM and Raman spectroscopy. Graphene co-planar waveguide (G-CPW) transmission lines of various widths and lengths were then constructed on silicon wafers because they are used in the integration of passive and active components in microwave monolithic integrated circuits. To minimize the reflection at the input port and thus maximize signal transmission through the graphene co-planar waveguides, we designed the transmission lines to have a characteristic impedance of 50 Ω. Simulation of the G-CPW test structure was first performed using CST Microwave Studio electromagnetic simulator to predict its RF performance and optimize the geometrical parameters. Then G-CPW test structures were patterned using electron beam lithography and wet chemical etching on SiO2/Si substrates, followed by RF measurements with a wafer probe connected to a vector network analyzer to obtain S-parameters. By curve-fitting the experimental results with simulation, graphene parameters were subsequently extracted. Scattering parameter measurements of the samples obtained at frequencies up to 20 GHz revealed that GNR has high potential to be used in RF applications. © 2014 IEEE.