Reactor Irradiation of Semiconductor Devices

This experiment surveyed some parameter changes of several types of semiconductor devices exposed to a reactor radiation environment. Twelve irradiated and eight control specimens from production stock of two diode and eleven transistor types constituted the experimental groups. The experimental region of the reactor was initially flux mapped, and a flux determination was made for each irradiation. The total dose was about 1014 fast neutrons/cm2 and 108 ergs/gm(c) of gamma rays. Measurement of electrical parameters before, during, and after irradiation indicated a tolerance limit for some devices. The most radiation-resistant transistors measured were silicon double-diffused mesa units types 2N702 and 2N726, and germanium diffused-base mesa units types 2N710 and 2N797. Voltage regulator and switching diodes were hardly affected. Radiation tolerance was greater in the devices with a narrow base region. The increase in tolerable dose with increasing gain-band-width product is less for germanium than for silicon. There appears to be only a small difference between silicon and germanium in allowable dose for very-high-frequency devices.