Characterization of contact properties at interface between metal and graphene up to 15 GHz

• Main Authors: Shohei Kosuga, Ryosuke Suga, Takeshi Watanabe, Osamu Hashimoto, Shinji Koh
• Format: Article
• Language: English
• Published: Wiley 2021-05-01
• Series: Engineering Reports
• Subjects: contact properties; coplanar waveguide; graphene; microwave; optically transparent antennas
• Online Access: https://doi.org/10.1002/eng2.12325

Abstract The contact properties between metal and monolayer chemical vapor deposition (CVD) graphene were investigated. Coplanar waveguides (CPWs) composed of CVD graphene‐based signal lines and Au‐based ground lines were fabricated. The S‐parameters of the CPWs were experimentally measured from 1 to 15 GHz. The contact properties were analyzed using a lumped component‐based equivalent circuit model, which consists of the experimentally determined parallel contact resistance and the parallel contact capacitance. The calculated S‐parameters of the model roughly agreed with the measured ones, which indicated that the model was suitable for analyzing the contact properties between metal and graphene up to 15 GHz. Because the impedance of the contact capacitance (4.8 × 10−3 Ω) was four orders of magnitude lower than that of the contact resistance (50 Ω) at 15 GHz, the current flow was more capacitive and efficient than that in the DC band. The ratio of power consumption and power storage in the microwave band to the total power consumption in the DC band decreased with increasing frequency and increasing contact capacitance. Therefore, higher contact capacitance is preferable in designing microwave devices with a metal/graphene‐based feeding structure, such as antennas and transmission lines.