Visualizing Intercalation Effects in 2D Materials Using AFM-Based Techniques

Intercalation of two-dimensional materials, particularly transition metal dichalcogenides, is a noninvasive way to modify the electronic, optical, and structural properties of these materials. However, research regarding these atomic-scale phenomena usually relies on using ultrahigh vacuum techniques, which are time-consuming, expensive, and spatially limited. Here we utilize atomic force microscopy (AFM)-based techniques to visualize local structural and electronic changes of the MoS₂/graphene/Ir(111) caused by sulfur intercalation. AFM topography reveals structural changes, while phase imaging and mechanical measurements show reduced Young's modulus and adhesion. Kelvin probe force microscopy highlights variations in surface potential and work function, aligning with intercalation signatures, while photoinduced force microscopy detects enhanced optical response in intercalated regions. These results demonstrate the efficacy of AFM-based techniques in mapping intercalation, offering insights into tailoring 2D materials' electronic and optical properties. This work underscores the potential of AFM techniques for advanced material characterization and the development of 2D material applications.