A conductive AFM tip is biased relative to the sample, creating electrostatic interactions that vary as the tip moves across regions with different surface charge or potential. Those variations modify the cantilever response, producing spatial contrast in the recorded signal. The resulting map can therefore reveal electrical nonuniformity that is not evident from surface structure alone.
Electrostatic interactions influence several measurable cantilever behaviors, including deflection, oscillation amplitude, and resonance behavior. Monitoring these responses converts a local electrical interaction into an experimentally recorded signal. Selecting the response that changes during scanning allows researchers to characterize charge or potential variations across materials and devices at nanoscale resolution.
A controlled lift height separates the electrical measurement from the surface-tracing portion of the scan. Maintaining that height while the tip moves helps record electrostatic interactions across the sample in a consistent scanning geometry. This condition is particularly relevant when comparing charge or potential variations between locations on semiconductor, dielectric, or nanostructured surfaces.
Contrast can arise from differences in surface charge, electrical potential, or charge-trapping behavior. Because the cantilever responds to electrostatic interactions, regions with different electrical states can produce different recorded signals during scanning. This makes the technique useful for examining electrical variations in semiconductors, dielectric films, nanostructures, and related device materials.
The measurement begins by positioning a conductive AFM tip over the sample and applying a bias relative to it. The tip then scans the surface, often while maintaining a controlled lift height. During this motion, the instrument records changes in cantilever deflection, oscillation amplitude, or resonance behavior, producing a nanoscale map of electrical interactions.
Physicists apply the technique when they need spatial information about electrical behavior in materials or devices. It supports characterization of semiconductors, dielectric films, and nanostructures, while also helping investigate charge trapping, device failure, and nanoscale energy or transport phenomena. These applications connect local electrostatic measurements with broader questions about electronic-material performance.