Abstract
A molecular dynamics model was developed to investigate the effects of scanning parameters on amplitude-modulation atomic force microscopy (AM-AFM) groove-depth characterization in few-layer graphene. The simulated groove depth was defined by the steady-state amplitude difference between a flat reference region and the groove center. Increasing the theoretical groove depth changed the simulated topography from U-shaped to V-shaped and increased depth underestimation. The simulated groove depth also varied nonmonotonically with drive amplitude and initial tip–sample distance, indicating that appropriate parameter combinations can improve agreement with the theoretical groove depth. Comparisons with previously published AFM experiments provided qualitative support for the geometrical limitations of groove-depth characterization and the sensitivity of height measurements to scanning parameters. Analysis of the tip–sample force, atomic normal virial stress, and local shear strain showed that depth characterization was not determined solely by the overall interaction force. Instead, it was associated with the spatially nonuniform mechanical responses near the groove edges and bottom, which reflect the combined effects of tip geometry, local tip–sample interactions, and graphene deformation. Weak interactions resulted in a limited mechanical response at the groove bottom, whereas stronger interactions could increase local deformation without further improving the reconstructed groove depth. These findings provide a theoretical basis for selecting AM-AFM scanning parameters and understanding the microscopic mechanisms underlying topographic characterization of two-dimensional nanostructures.