Space-Charge-Limited Current in Neutron-Irradiated Silicon, with Evidence of the Complete Lampert Triangle

A theoretical model proposed by Lampert in 1956 suggests that all single-carrier conduction possibilities in solids, with discrete trapping levels and under constant mobility, are limited within a triangular region on a log-current-versus-log-voltage plot. Lampert's triangle is bounded by Ohm's law, Child's trap-free square law for solids, and an essentially vertical traps-filled-limit line. This paper reports the experimental observation of two of the bounding sides of this triangle, with the theoretically calculated third side fitting the experimental data very well, when based upon measured parameters using two methods of attack. The observations were made on a fast-neutron-irradiated silicon chip with gold-alloy electrodes, at 77^∘{}K. The behavior is principally due to the trapping character of the well-known oxygen-vacancy A center, which is activated by the neutron irradiation.