Surface barrier detectors using aluminum on n- and p-type silicon for α-spectroscopy

We describe the method by which surface barrier detectors (SBD) can be constructed from p- and n-type high-purity silicon (Si), with aluminum (Al) as a rectifying contact. This material has as properties: firm adhesivity to silicon, excellent light-tightness and low stopping power for charged particles, that are ideal for the entrance window. For the ohmic contact, we have used different metals: Al, gold (Au) plus antimony (Sb) mixture and AuSb alloy, with appropriate chemical treatment during the fabrication process. Electrical measurements have given the desired properties for the detection of charged particles. Unencapsulated SBDs show a low leakage current and an excellent long-term stability both in air and in vacuum. The energy resolution for the 5.486 MeV α-particle varies from 17 to 22 keV for detectors with sensitive area 20–80 mm2.