Thanks to the TCS preparation, XPS line scans performed could provide chemical and electronic information about the buried interfaces. The chemical composition reveals that the GaInP layers, as well as the Ge substrate, were significantly oxidized along the TCS. The presence of surface states induces Fermi level pinning to the exposed surface of the TCS and leads to EF-EVB measurements that contradict the doping levels measured by electrochemical capacitance voltage profiling of the prepared layers.