Characteristics of GaAs Heterojunction FETs (HFETs) and Source Follower FET Logic (SFFL) Inverters Exposed to High Energy Neutrons

GaAs heterojunction field effect transistors (HFETs), and inverters and ring oscillators comprising HFETs have been exposed to neutron fluences of 5 x 10 sup 13 n/cm sup 2 to 1 x 10 sup 15 n/cm sup 2 to evaluate the characteristics of HFET integrated circuits in a weapons environment. 

The HFETs irradiated in this study were fabricated at the AT&T Bell Laboratories GaAs Pilot Line and exhibited pre-irradiation transconductances of approximately 120 mS/mm and threshold voltages of -0.75 V. The degradation in device transconductance and the device threshold shift as a function of neutron fluence are shown in Figs. 1 and 2, respectively.