Investigation of the topography-dependent current in conductive AFM and the calibration method

Abstract

The topography and the electrical properties of materials are two crucial characteristics in determining their functionalities. Conductive atomic force microscopy (CAFM) is widely recognized for its ability to independently measure the topology and conductivity of the sample surface. The increasing trend towards miniaturization in electrical devices and sensors has led to an urgent demand for enhancing the accuracy of CAFM characterization. However, the sample's topography may affect the current measured by CAFM, leading to an inaccurate estimation of the sample's conductivity. Herein, we investigated the existence of topography-dependent current that originates from changes in capacitance between the probe and sample in CAFM testing. A linear correlation between the current and topography has been established using both experimental and theoretical methods. A calibration method based on this linear correlation has been proposed to eliminate the current error induced by the uneven surface of both insulators and conductors. This work will yield substantial advantages for research requiring high-precision CAFM testing.Comment: Corrected typo