Neutron-Induced Damage to Silicon Rectifiers

As transistors become more radiation tolerant, renewed importance must be attached to the degradation of diode performance in a radiation environment. The dominant effect in most rectifiers is the increase in series resistance due to the removal of majority carriers from the conduction process in the base material. The initial conductivity of the base material and recent experimental data on carrier removal rates are used to predict the amount of degradation in the electrical characteristics of a rectifier exposed to a neutron environment; the initial conductivity of the base material may be obtained from diode design information or it may be estimated from the value of the avalanche breakdown voltage. Experimental data are presented which, in general, substantiate the predictions. In particular, diodes with a breakdown voltage of less than 100 volts appear to be usable to neutron fluxes in excess of 1014 n/cm2. Gold doping seems to increase radiation tolerance.