Fabrication of surface-barrier nuclear particle detectors from p-type silicon

Abstract

A simple method is described by which surface barrier detectors of excellent performance can be constructed from p-type silicon of resistivity up to at least 5000 ohm·cm. The rectifying front electrode is a vacuum evaporated aluminium film and the rear electrode is a similar film of gold. An important feature of the method is that the silicon surface is prepared by gradually quenching the CP4A etchant with concentrated nitric acid, followed by slow decanting with deionised water. Unencapsulated detectors show excellent long term stability in both air and vacuum. For detectors of area 20 mm 2 typical energy resolution (fwhm) for 5.5 MeV alpha particles is 30 keV. Thin totally depleted detectors have been successfully made in this way and the surface preparation technique appears to have advantages in the fabrication of conventional surface barrier detectors from n-type silicon.