Effects of Ionizing Radiation on Dielectrically Isolated Junction Field Effect Transistors

Transient (electron) and total (gamma) ionizing radiation effects on dielectrically isolated junction field effect transistors (DIJFET´s) are presented as a function of dielectric isolation configuration, dose, dose rate, and bias. Four different device structures of DIJFET´s are studied. The three device types incorporating p+ buried layers to separate the SiO2 dielectric from the active n-type channel region are shown to be relatively immune to permanent effects induced by ionizing radiation up to total doses of 108 rads (Si), whereas the device structure utilizing dielectric isolation by simply replacing the substrate junction with a silicon dioxide dielectric showed serious degradation above 105 rads (Si). The DIJFET structures utilizing p+ buried layers are characterized in a transient ionizing radiation environment up to 6×109 rads (Si)/sec and in a total ionizing environment up to 108 rads (Si). The transient photocurrent response of the DIJFET was experimentally determined to be one-fourth that of a regular JFET with the same surface geometry.