Analysis of the lateral resolution of electrostatic force gradient microscopy

This is the authors' abstract. We don't add key points for this paper.

Signal measured by electrostatic force gradient microscopy (EFGM) is the z-gradient of the electrostatic force acting between the probe of an atomic force microscope (AFM) and the surface under study. A model is presented for calculating the z-gradient of the electrostatic interaction of the AFM probe with local charges in a dielectric layer at the surface. In the EFGM mode, the interaction of charges with only the probe tip apex should be taken into account. In this approach, a simplified expression can be derived for calculating the z-gradient of the electrostatic force. The model makes it possible to estimate the lateral resolution limit for EFGM imaging of individual charges and to simulate experimental EFGM images as a function of the tip-surface distance and the tip radius. The adequacy of the model was confirmed by quantitative simulation of the experimental EFGM images of local charges injected from the AFM probe into a planar array of Si nanocrystals in a thin SiO2 layer on a Si substrate.