Optimizing electrical AFM probing for 2D materials: The crucial role of tip-sample electrical interactions and back contact configurations

Abstract

As electrical atomic force microscopy (AFM) gains popularity for characterizing two-dimensional (2D) materials, understanding the relationship between analytical conditions and nanoscopic material properties is crucial. This study focuses on contact-mode electrical methods, using MoS2 as a reference material and conductive AFM (C-AFM) as the analysis technique. We investigate the impact of back contact configuration, tip-sample pressure, voltage polarity, and moisture-induced surface contamination on the extraction of localized electrical properties, including in-plane leakage current and defectivity. Our findings highlight the importance of balancing tip-sample contact resistance and the physical distance between the probe and back contact when assessing in-plane leakage current. Additionally, we explore how tip-sample to back contact distance affects the extraction of Schottky barrier height (SBH) using current-voltage (I-V) spectroscopy. Given the growing interest in 2D materials and the significant role of electrical AFMs in their characterization, optimizing these methods can contribute to the successful transition of 2D materials from the lab to manufacturing.