Nanoscale Scanning Microwave Impedance Microscopy on Advanced Functional Materials

We present the design and experimental results of near-field scanning microwave impedance microscopy (MIM). By sending the excitation 1GHz signal to a shielded cantilever probe and detecting the reflected signal, the MIM electronics measure the real and imaginary components of the tip-sample admittance to form the corresponding MIM-Re and MIM-Im images. The system can be installed on commercial atomic-force microscope platforms or cryogenic chambers. Nanoscale electrical imaging on advanced materials, such as monolayer MoS2 flakes, BaTiO3-Ge heterostructures, and ZnO field-effect transistors, have been obtained using the near-field microwave microscope.