RADFET as a sensor and dosimeter of gamma-ray irradiation

Gamma-ray irradiation and post irradiation response at room and elevated temperature have been studied for RADFETs with gate oxide thickness of 100 nm with gate polarization during irradiation of 5 V as well as for RADFETs with gate oxide thickness of 400 nm with gate polarization of 0, 2.5 and 5 V. The response was observed on the basis of threshold voltage shift, ΔV_T. Approximately linear dependence between ΔV_T and absorbed dose was established. During the annealing at room temperature the RADFETs with the gate thickness of 400 nm and the gate polarization during irradiation of 2.5 V and 5 V shows the tendency in ΔV_T decrease, while for 400 nm RADFETs with the zero gate polarization during irradiation and 100 nm RADFETs ΔV_T remains approximately unchanged. Continued annealing at 120°C leads to the decrease of ΔV_T. For 100 nm RADFETs, ΔV_T decreases to zero while for 400 nm RADFETs such decrease is considerably smaller.