Neutron Radiation Damage in Silicon Transistors

Recombination statistics for the neutron-induced base current component

“…Four basic processes were assumed to be involved in this recombination-generation through the recombination centers: 1) hole capture; 2) hole emission; 3) electron capture; and 4) electron emissionl,2,4. In order to study the nuclear radiation effects on silicon p-n junction transistors, the last component in Table I-1 was considered throughout this in- [8][9][10][11][12] vestigation. This component was identified by Goben and has the following expression One important limitation of transistors operated in a neutron environment is the decrease in transistor current gain observed upon exposure to neutron irradiation.…”

“…space-charge region, when the transistor is [8][9][10][11][12] exposed to neutron irradiation it was shown that the emitter efficiency is indeed a very sharply decreasing function of neutron fluence and is responsible for a large fraction of the neutron degradation of transistor current gain. Transistors provide a definite advantage over semiconductor bulk materials for studying radiation effects since they permit measurement of base lifetime in the range from several hundred microseconds down to the nanosecond range, .whereas determination of lifetime by photoconductivity in bars of semiconductor material is in general limited to the range greater than one microsecond.…”

“…The reciprocal slope term, n, in exp(qV /nkT) was ob- [8][9][10][11][12] served to increase with decreasing temperature from 1.5…”

“…The emergence of the neutron-induced component of base current reduces the emitter efficiency and thereby causes the degradation of transistor current gain. 8 It can be expected that the dominant effect causing changes in transistor parameters is the decrease in minority carrier lifetime and degradation of the emitter efficiency.…”

“…Based on the model for the neutron-induced base current [8][9][10][11][12] component developed by Goben and the recombination statistics in the space-charge region given by Sah et al 5,6 this paper develops a recombination statistical model for the neutron-induced base current component. This model can be used for predicting the base current of any diffused junction transistors and may be extended to a more general model for other types of transistors.…”