Nuclear Radiation Enhancement of Transistor Forward Gain at High Frequencies

This investigation has characterized the effects of fast neutron bombardment on a typical n-p-n transistor (2N914) of a common emitter amplifier operating at high-frequencies (>100 MHz) by means of s-parameter measurements from 120 MHz to 350 MHz, inclusive, every 10 MHz. The changes in the four (4) s-parameters and the trends and consequences of neutron bombardment are examined pictorially on graphs. The general effect of fast neutron bombardment is to decrease the magnitude of each s-parameter for frequencies below z · fT (where z = (Ф/1013)0.1). However, if the device is operating above z · fT, the magnitudes of s11 (input reflection coefficient) and s21 (forward insertion gain, which may be approximated by hfe) increased above the pre-irradiation values, which would not be expected from previous work carried out at d-c and low frequencies.