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 V(f) at a constant current when exposed to neutrons. The change in V(f) is a measure of neutron dose. Variation in V(f) with neutron dose is linear but has different slopes for regions below 2.5 Gy and above it. In or der to use a single electronic reader instrument for measuring a chang e in V(f), there is a requirement of fabricating diodes of unique V(f) , which is not always possible due to minor deviation in the quality o f wafer used. A method of exposing diodes to neutrons has been used to arrive at desired narrow V(f) for the p-i-n diodes produced in differ ent 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 on ly one slope beyond 2.5 Gy.