High-Frequency Characterization of Contact Resistance and Conductivity of Platinum Nanowires

Contact resistance and conductivity of individual platinum (Pt) nanowires (NWs) embedded in coplanar waveguide structures are investigated at high frequencies. Two approaches to extract the NW conductivity and contact resistance from two-port S-parameters are developed. The first approach is based on transmission-line theory, while the second approach is based on a lumped-element physics-based model. Full-wave and circuit simulations are used to aid validation and the systematic analysis of both methods. Simulations are compared to calibrated on-wafer measurements of individual Pt NWs. The studies of the transmission-line-based approach reveal that the contact resistance can be determined accurately, but the obtained conductivity is inaccurate. By contrast, the lumped-element approach produces accurate results for both the contact resistance and conductivity of Pt NWs. The lumped-element method is used to determine the contact resistance of about 50 Ω and conductivity of 0.013 times the bulk conductivity of Pt for fabricated Pt NWs with 300-nm diameter.