The incorporation behaviour of antimony and tin in Ge was studied by means of Auger electron spectroscopy. By comparing the measured intensity ratios with a simple incorporation model, we find that Sn is stronger segregating than antimony. The activation energies are 0.34 and 0.27 eV, respectively. Using both materials in order to improve the interface sharpness of short-period Si/Ge superlattices, we can show that antimony improves the superlattice structure up to growth temperatures of 600°C, while with tin the superlattice growth is destroyed.