Amorphous Germanium as an Electron or Hole Blocking Contact on High-Purity Germanium Detectors

Experiments were performed in an attempt to make thin n+ contacts on high-purity germanium by the solid phase1 epitaxial regrowth of arsenic doped amorphous germanium. After cleaning the crystal surface with argon sputtering and trying many combinations of layers, it was not found possible to induce recrystallization below 673K. However, it was found that simple thermally evaporated amorphous Ge made fairly good electron or hole blocking contacts. Excellent spectrometers have been made with amorphous Ge replacing the n+ contact. As presently produced, the amorphous Ge contact diodes show a large variation in high-voltage leakage current.