A combination of electrostatic force microscopy (EFM) and scanning surface potential microscopy (SSPM) is used to quantify nanometer scale field variations for the general case of electronically inhomogeneous surfaces. The specific example illustrated here is the intersection of a Σ5 grain boundary in donor doped SrTiO3 intersecting the (100) surface. ‘The topographic structure is compared to the surface potential, the positive and the negative electrostatic force images in figure 1. The EFM contrast changes sign with the polarity of the applied bias, as expected for an electrostatic attractive/repulsive interaction. There is a significant localization of surface potential at the grain boundary that is manifest as a protrusion in the SPPM image.

To quantify the properties at the surface, rather than above the surface where the measurements are acquired, a relationship connecting the sample-tip interaction is required. It has been shown that models based on simple geometric assumptions do not represent the behavior well.