The electron Schottky-barrier height (SBH) of platinum germanide diodes on germanium (PtGe/Ge) is tuned by means of incorporation of phosphorous dopants from a spin-on-dopant resist. Thereby a highly doped surface layer on Ge substrates is formed in a rapid thermal diffusion process before the formation of PtGe. Applying a diffusion process of the P atoms at temperatures above 580 degrees C, an ohmic contact behavior is found for the originally Schottky-type barrier diodes and evidence is given for a lowered electron SBH. The contacts exhibit barrier heights to electrons as low as Phi(B,e) = 0.16 eV. In contrast, increased barrier heights for holes of Phi(B,h) = 0.45 eV are found. The results of the electrical characterization are further supported by time of flight secondary-ion mass spectrometry measurements where a pileup of P dopants at the PtGe to Ge interface region is observed. In summary, a damage-free process scheme for the reduction in the electron SBHs in PtGe/Ge diodes is given. The presented approach can pave the way to ohmic-type n-contacts to germanium and is applicable to planar as well as three-dimensional device structures. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3425750] All rights reserved.