Nonalloyed ohmic contacts to n-GaAs with contact resistances (ρc) below 1·0×10−7 Ω cm2 have been obtained using a Ge/GaAs heterojunction system. Metals are evaporated on heavily arsenic-doped germanium (Ge) layers grown on GaAs. Low values of ρc result from the low Schottky barrier height (≈ 0·50 eV) and the high doping levels obtainable for n-Ge(≈ 1020 cm−3).