The effects of gamma radiation on two high-speed bipolar fabrication processes

The continuing development of the Superconducting Supercollider has influenced the need for semiconductor devices that can operate in a radiative environment and maintain a high operating speed and a significant degree of noise immunity while operating at low currents. Several npn bipolar transistors were obtained from two new high-speed fabrication processes developed at Hewlett-Packard Corporation. The devices were characterized by their basic dc parameters and noise characteristics and exposed to 5 Mrad(Si) of gamma radiation. The devices were retested to determine the effect of the irradiation. Both graphical and tabular results are presented for comparison. The results of the study indicate that the devices suffer a significant decrease in the basic dc parameters, particularly a decrease in the forward current gain of more than 50%, and a decrease in the Early voltage of nearly 30%. The noise characteristics showed a significant increase in both the equivalent noise current and the equivalent noise voltage of the devices.