Measurement Techniques for RF Nanoelectronic Devices: New Equipment to Overcome the Problems of Impedance and Scale Mismatch

The emergence of new materials (nanowires, nanotubes, graphene tapes, and thin films) and devices with nanoscale dimensions give rise to the necessity for developing dedicated techniques that will allow their electrical characterization at high-frequency range. In this article, two possible views have been highlighted to tackle the issue of the measurement of high-impedance nanoscale devices. The first solution is based on the integration of a high-impedance reflectometer and a nanoscale device on the same chip. The microwave impedance of a single CNT has been successfully measured up to 6 GHz using this technique. The second solution consists of inserting an adjustable microwave interferometer between a traditional VNA and the high-impedance device. The interferometer allows adjustment of the impedance to be measured to the highest measurement sensitivity of the measurement system. In particular, capacitances down to 0.35 fF have been measured with an error estimated to be less than 10% using the interferometric technique combined with a scanning microwave microscope. These proofs of concept on one-port nanodevices open the route towards the case of two-port active devices with high impedance. Advances in the manufacturing of next-generation nanodevices will depend on our ability to measure electrical properties and performance characteristics accurately and reproducibly at the nanoscale regime over a broad frequency range.