Three-dimensional finite-element simulations of a scanning microwave microscope cantilever for imaging at the nanoscale

Abstract

We use three-dimensional finite-element numerical simulations to fully characterize the electromagnetic interactions between a metallic nano-tip and cantilever that are part of a scanning microwave microscopy (SMM) system and dielectric samples. In particular, we use this rigorous computational technique to analyze and validate a recently developed SMM calibration procedure for complex impedance measurements in reflection mode. Our simulations show that relatively small changes in the conductivity of the substrates can cause significant variations in the measured reflection coefficient. In addition, we demonstrate that the bulk systemic impedance is extremely sensitive to modifications of system parameters, namely, variations in the cantilever inclination angle as small as 1° cause changes in system impedance that can be larger than 10%. Finally, the main experimental implications of these results to SMM imaging and calibration are identified and discussed.