There is increasing interest in the quantitative characterization of nanometer-scale semiconductor alloy layers, such as those of SiGe or AlGaAs. Electron holography, which has the ability to detect small changes in mean inner potential Vo, can in principle provide information about local changes in composition. However, the measurement of absolute values of Vo is not always straightforward and values for only a few materials are known with confidence. In this study, we measure Vo for Ge using electron holography, and we compare our experimental data with calculations. The holographic approach that we use to measure Vo is described in the paper of Gajdardziska-Josifovska et al. The Ge samples were nominally 90° cleaved wedges from a <100> wafer. Holograms were recorded on a Philips CM200 FEG equipped with a Gatan 794 CCD camera, and data were obtained for several crystal tilts (determined from diffraction patterns) to assess dynamical contributions to the phases.