The need to determine the electrical properties of semiconductor junctions with high spatial resolution is as pressing now as ever. One technique that offers the possibility of quantitative high-resolution mapping of two- and three-dimensional electrostatic potential distributions is off-axis electron holography. In this study, we review some of the issues associated with interpreting phase shifts measured using off-axis electron holography, and we describe how a quantitative determination of the dopant-related electrostatic potential can be achieved for device structures. Issues that include the presence of surface "dead" layers, external electrostatic fringing fields, variations in specimen thickness and dynamical diffraction are discussed, and their impact on the quantification of results obtained using off-axis electron holography is examined.