Abstract The rectification properties of sputtered amorphous germanium contacts made under a variety of conditions on germanium detectors have been measured as a function of temperature and electric field. The leakage current increased as a function of voltage above depletion voltage. The rectifying amorphous–crystalline heterojunction theory derived by Dohler and Brodsky describes the behavior well. Values of barrier height were measured to be ∼0.30–0.35 eV and the density of states was found to be N F ∼10 18 eV −1 cm −3 .