Neutron dosimetry using the bipolar transistor Gummel-Poon model parameter C2

Abstract In this study a comparison is made between dc current gain, h FE , and the base-emitter leakage emission coefficient, C 2 , of bipolar transistors for use as an indicator in neutron dosimetry. 2N2484 and 2N2222 npn bipolar transistors were subjected to 1 MeV equivalent neutron irradiation ranging from 1 × 10 12 n/cm 2 to 1 × 10 16 n/cm 2 using a TRIGA reactor. Results indicate that the Gummel-Poon model parameter C 2 is significantly more sensitive than h FE to values of neutron fluence to which a transistor is exposed. Linear modeling equations indicate that the increase in C 2 after neutron irradiation, like h FE , is due to displacement of silicon atoms and can be used in neutron dosimetry. A “ C 2 damage constant”, K C 2 is defined which can be used in modeling equations to estimate the fluence of an unknown neutron field. Compared to h FE , a significant improvement in accuracy is obtained when C 2 is used to determine the fluence of an unknown neutron field at low fluence levels. Some improvement is also observed at higher fluences.