Can a pinned Fermi level at a semiconductor surface be moved by deposition of heavily doped overlayers? We calculate the position of the Fermi energy in the gap for structures composed of a bulk semiconductor substrate and a heavily n-type doped Ge overlayer. This structure is the basis for the new Ohmic contact for n-GaAs proposed by Waldrop and Grant [Appl. Phys. Lett. 50, 250 (1987)], and relevant to our Ge/InP data where the Ge overlayer is naturally doped by intermixed P from the substrate. Using the defect model, we find that 10 Å of heavily doped Ge can move the Fermi energy towards the conduction-band minimum, even if it is initially pinned by induced defects. This is due to the electrons from the heavily doped overlayer filling all available interface defect levels. Modeling of a final metallic overlayer to complete the Ohmic contact is also discussed.