Scanning impedance microscopy (SIM): A novel approach for AC transport imaging

Scanning Impedance Microscopy (SIM) is one of the novel scanning probe microscopy (SPM) techniques, which has been developed to taking image from sample surface, providing quantitative information with high lateral resolution on the interface capacitance, and investigating the local capacitance–voltage (C–V) behavior of the interface and AC transport properties. The SIM is an ordinary AFM equipped with a conductive tip (C-AFM), which is imaged by non-contact mode with harmonic detection. This method is based on the local detection of surface potential or the amplitude and phase of local voltage oscillations induced by a lateral periodic bias applied across the sample. SIM can simultaneously collect the amplitude and phase signals and image the morphology of the surfaces; afterward, calculate the corresponding histogram for each map. Hence, the amplitude and phase signals of the surface potential oscillations are related to the sample impedance. SIM can also be integrated with Surface Potential Microscopy (SSPM). The combination of these techniques provides an approach for the quantitative analysis of local DC and AC transport properties. These advantages give SIM a higher resolution than other SPM techniques and indicate its immense potential for vast applications. The combination of SSPM and SIM were demonstrated for a Schottky diode, but can be applied to any semiconductor device.