Antimony sputter deposition and subsequent diffusion annealing in controlled atmosphere was implemented on Ge wafers, for achieving an optimized n+ doping aimed at the final application of these doped contacts to Ge-based radiation detectors. Two approaches were adopted for n+ doping: diffusion from Sb source sputtered directly on the Ge surface, and diffusion from a remote dopant source. Surface morphology was specifically investigated by electron (SEM-EDS) and atomic (AFM) microscopies. Diffusion profiles were characterized by Secondary Ion Mass Spectrometry (SIMS). The remote doping, obtained by using a Sb-coated Si wafer placed close to the Ge substrate during the diffusion annealing, allowed to attain defect-free surface morphologies and diffusion profiles compatible with well assessed equilibrium diffusion models.