Measurability Issues in the Radio-Frequency Characterization of Carbon Nanotubes

We discuss two measurability issues plaguing conventional on-wafer RF measurements with a network analyzer when dealing with quasi 1-D systems, such as carbon nanotubes. Those small-geometry devices typically exhibit an impedance on the order of h/(2e)²≈ 12.9 kΩ, resulting in a large intrinsic mismatch with the 50Ω reference impedance of the network analyzer. We show that the accuracy of the network analyzer is greatly degraded by this mismatch. In addition, the de-embedding of the test fixture is shown to degrade even further the measurement uncertainty. We then propose a potential solution to circumvent these accuracy problems.