Radiation effects on Si-JFET devices for front-end electronics

Low noise monolithic silicon junction field effect transistors (Si-JFETs) have been exposed to /sup 60/Co /spl gamma/-rays and to fast neutrons (1 MeV) to study radiation-induced effects on their dc characteristics and noise. The devices have been irradiated and measured at a stable cryogenic temperature (T/spl sim/90 K) up to an integrated 550 kGy (55 Mrad) dose of gamma radiation and to a total fluence of 4/spl times/10/sup 14/ n/cm/sup 2/. At cryogenic temperatures, a variation in some of the dc characteristics of the transistors has been observed as a result of the neutron-induced lattice damage. The pinch-off voltage and the maximum drain current I/sub DSS/ are the most affected de parameters. A noise increase induced by either the /spl gamma/-ray or neutron irradiation has also been observed. The activation energies of some of the radiation-induced defects have been extracted from noise measurements at different temperatures after irradiation. Annealing effects on both dc properties and noise have been observed while performing thermal cycles between cryogenic and room temperatures.