The space charge relaxation behaviour of silicon diodes irradiated with 1 MeV neutrons

The current–voltage characteristic of silicon diodes irradiated with 1 MeV neutrons demonstrates an ohmic behaviour and a resistance grouped around the theoretical maximum value. These two effects suggest that radiation damage in silicon induces relaxation behaviour which results in pinning of the Fermi level at mid-gap. Several crude measures of the relaxation-like behaviour have been devised and are presented. The measures have been determined for three sets of silicon diodes (pure, high resistivity gold-doped and low resistivity gold-doped) and are discussed in relation to the activation energy and also to the two measures of radiation damage. Using these different measures it is possible to identify relaxation-like devices and also to determine the level of damage within an irradiated sample.