Neutron Radiation Induced Degradation of Diode Characteristics

Abstract : Neutron radiation effects on diode current-voltage characteristics have been studied for a variety of diode over 1x10 to the 13th to 3x10 to the 15th n/sq. cm 1 MeV equivalent neutron fluence range. A classification scheme consisting of three types of neutron effects on diode forward characteristics is proposed here for the first time. For constant forward current IF higher than that in the generation-recombination regime, the diode voltage VF either increases with fluence phi (Type 1 diode), on V sub F first decreases with phi at lower fluence levels and then increases with phi at higher fluence levels (Type 2 diode), or VF decreases with phi at all fluence levels used in this work (Type 3 diode). Most of the previous results on p-n junction diodes correspond to Type 1 diode results. Type 2 diode results are rather rare in the literature. Several examples of Type 2 diode results are presented here. Type 3 diode results are reported here for other types of diodes not reported earlier. These results are explained qualitatively in terms of the theories for a p-n junction and for radiation effects on semiconductors. It is shown here that a Type 3 diode could be developed as a high neutron fluence monitor with three orders of magnitude higher upper limit than the Harshaw p-i-n diode neutron fluence monitor under evaluation at the Us Army Aberdeen Proving Grounds, Aberdeen, Md. The results also suggest a methodology for radiation hard diode development.... Neutron, Radiation effects, Diode characteristics, Neutron fluence monitor, Radiation hardness.