Fast neutron irradiation for fabrication of narrow forward voltage p-i-n diodes

Wide base p-i-n diodes show an increase in the forward voltage Vf at a constant current when exposed to neutrons. The change in Vf is a measure of neutron dose. Variation in Vf with neutron dose is linear but has different slopes for regions below 2.5 Gy and above it. In order to use a single electronic reader instrument for measuring a change in Vf, there is a requirement of fabricating diodes of unique Vf, which is not always possible due to minor deviation in the quality of wafer used. A method of exposing diodes to neutrons has been used to arrive at desired narrow Vf for the p-i-n diodes produced in different batches. Further the raw p-i-n diodes when exposed to about 2.5 Gy neutrons, before using them for dosimetry, need a readout instrument for simple amplification as the neutron response of the diodes give only one slope beyond 2.5 Gy. (orig.)