Electric Force Microscopy (EFM) and Surface Potential (SP) imaging are nondestructive AFM techniques for detecting electric field gradients and surface potential variations on insulating, conducting and semiconducting materials. Requiring little or no sample preparation, characterization is done in air on test structures and materials in research on chip- or wafer-level devices, and even on completed, powered ICs. Applications range from monitoring fabrication processes, to failure analysis, to quantifying electrical properties of materials. In addition to imaging, a conductive AFM tip with a controlled voltage can be used to modify electrical properties of materials locally, e.g., polarization of ferroelectric films.